Source: http://www.abarim-publications.com/Meaning/Tattenai.html

🔼The name Tattenai in the Bible

The name Tattenai (or Tatnai, as some translations have) occurs only in two chapters of the Book of Ezra (Ezra 5:3, 6, 6:6, 13).

Tattenai was a Persian governor of either Judea or an area somewhere close enough to Judea for Tattenai to team up with Shethar-bozenai and some others to meddle in the temple restoration affairs of Ezra and his colleagues. The sent a letter to king Darius to inform him about the project and to request that it could be verified that king Cyrus ever decreed it (Ezra 5:6-17).

King Cyrus' decree was dug up and reproduced and Tattenai and his buddies were told to buzz off (Ezra 6:6) and even to diligently provide the builders with provisions and protection (Ezra 6:13).

🔼Etymology and meaning of the name Tattenai

The name Tattenai is most probably Persian and may be a creative rendering of the name Ustanu (ושתני), which belonged to a Persian prefect in Syria under Darius (says BDB Theological Dictionary). And this latter name may have something to do with the word תסני (thasna), which occurs in Zoroastrian scriptures as sasna, meaning Teaching.

Much more interesting is the perspective of Alfred Jones (Dictionary of Old Testament Proper Names), who sees the name Tattenai (or rather Tatnai) as identical to a noun derived from a Persian verb that means to give. Hence Jones translates our name with Gift.

It should be noted that one of the many literary devices at the disposal of Hebrew scribes was transposition, and since the character of Tattenai swapped from bad guy to good guy, a trace of transposition wouldn't misdo him. And that brings us to the form נתתי (ntty), which means I Have Given, and which occurs frequently in the Bible (Genesis 1:29, 9:3, 9:13, 15:18, ...). Our name looks also like an extension of the form תתן (ttn), which comes from the same verb : she gave (Genesis 3:6, 16:3), you gave (Genesis 15:2, 28:22). And finally, our name is identical in form to תתני (ttny), which occurs in Lamentations 2:18 ('give yourself no relief'), Ezekiel 16:41 ('wages you shall not give again'), and Micah 1:14 ('you will give presents').

So whatever the name Tattenai may have originally have meant in Persian, to the Hebrews it was indistinguishable from an expression of the verb נתןnatan, meaning to give: